SCIENCE WATCH

SCIENCE WATCH; Chemists Duplicate Miracle of Saint's Blood

Published: October 15, 1991

THE preserved, clotted blood of early saints of the Roman Catholic Church liquefies on certain ceremonial occasions, drawing crowds of faithful pilgrims eager to witness the miraculous phenomenon. But a team of Italian scientists has conducted experiments showing that medieval chemists could easily have created imitation blood that would do the same thing.

In a report published by the British journal Nature, a group headed by Dr. Luigi Garlaschelli, a chemist at the University of Pavia, says that blood liquefaction can be explained in terms of a phenomenon called thixatropy. Certain substances, including some types of mayonnaise, are normally thick gels, but can be liquefied instantly by shaking or stirring. Part of the ritual of checking the miraculous blood of Saint Januarius, observed every few months in Naples, for example, involves inverting the blood's reliquary container. This simple act is enough to liquefy certain thixotropic gels, the authors note. Left to stand, such liquids soon revert to gels.

The Italian team prepared one type of imitation blood using a solution of ferric chloride and calcium carbonate. Another successful experiment involved extraction of material from animal gut, and subsequent treatment with iron oxide and sodium chloride. In these and other experiments, the scientists said, they produced a brownish material that clotted when left alone but was easily liquefied each time it was gently moved.

Is the famous liquefying blood of Saint Januarius a fake?

"The chemical nature of the Naples relic can be established only by opening the vial, but a complete analysis is forbidden by the Catholic Church," the scientists said. "Our replication of the phenomenon seems to render this sacrifice unnecessary."